Island



(No Model.)

O. D. ROGERS. DIE FOR MAKING ROLLED WOOD SOREWS.

No. 440,330. Patented Nov. 11,1890.

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' UNITED TATES CHARLES D. ROGERS, OF PROVIDENCE, RHODE ISLAND, ASSIGNORTO THE AMERICAN SCREW COMPANY, OF SAME PLACE.

DIE FOR MAKING ROLLED WOOD-SCREWS.

SPECIFICATION forming part of Letters Patent No. 440,330, dated November11, 1890.

Application filed August 4, 1890. Serial No. 360,864- (No model.)

To all whom it may concern.-

Be it known that I, CHARLES D. ROGERS, a citizen of the United States,residing at Providence, in the county of Providence and State of RhodeIsland, have invented certain new and useful Improvements in Dies forRolling Screw-Threads on Wood-Screws; and I do herebydeclare thefollowing to be a full, clear, and exact description of the invention,such IO as will enable others skilled in the art to which it appertainsto make and use the same, reference being had to the accompanyingdrawings, and to letters of reference marked thereon, which form a partof this specification.

In a patent of the United States granted to me September 20, 1887, No.370,354,1have described and claimed a novel form of die for developingthe threads of rolled wood-screws. In that die the ribs are representedas V- shaped, the Working-faces being truncated throughout their length,narrow at the coinmencement or entering end, and gradually divergingtherefrom to the opposite end, at which point the grooves (alternatingwith the ribs) are the exact counterpart of the thread produced upon thescrew by the dies. In that die the angle or inclination of the sides ofthe ribs to each other is constant from one end of the die to the other,although the 0 height of each rib and the depth of each groove isrepresented and described as varying throughout its length.

The object I have in View in my present improvement is to produce astronger and bet- 3 5 ter die, yet one in which the ribs shall retainall the characteristics and advantages possessed by my patented diebefore referred to.

To that end my invention consists, essentially, of a die having at thecommencement or entering end ribs and grooves of the same or a lessdepth than that of the grooves at the opposite or finishing end of thedie. By reason of such construction the ribs are much less liable tofracture or break during the process of hardening and tempering the die.Moreover, the die when put into use will last longer, owing to theincreased strength of the ribs at the front or entering end.

In the appended drawings, representing my improved die, Figure 1 shows aplan of the working-face of one die. The unshaded parts represent thefaces of the ribs. Fig. 2 is a longitudinal sectional view taken on theoblique line a; 00 of Fig. 1. Fig. 3 is a similar sectional view showinga modification of the depth of the grooves and ribs. Fig. 4 is anelevation of the front end of the die. Fig. 5

is a similar view showing the back end of the die where thecompletely-threaded screw leaves it. Fig. 6 is a transverse sectionalview taken on line t t of Fig. 1. Fig. 7 is a similar View taken througha pair of dies placed opposite to each other as in operation, showing ascrew between them in the act of having a thread developed on itssurface, 6 5 the section corresponding with line 0 0 of Fig. 1; and Fig.8 is a similar section taken on line p p.

In the drawings, A designates my improved die as a whole. The partsmarked aindicate the ribs adapted to be impressed into the screw-blankssurface, and the shaded parts marked 6, Fig. 1, indicate the groovesbetween the ribs. The grooves are filled in or truncated at the front orentering end and are V- shaped at the opposite end. The bottom 0 of thegrooves may be parallel with the face of the ribs, as shown in Fig. 3,or inclined, as in Fig. 2, the depth being greatest at the back end ofthe die. In fact the bottom or depth of the grooves need to beconsidered only with reference to the gradual development of thescrew-threads in a radial direction; or, in other words, the depth ofthe groove at any point slightly exceeds the height of the metal raisedfrom the blank measured from the root of the thread at a correspondingpoint. Therefore the bottom of the grooves may be inclined substantiallyas indicated by the broken line m, Fig. 2.

The angle of the inclined sides of the ribs a is constant and uniformthroughout the length of the die, but the width of the face or top ofthe ribs is constantly Varying throughout or from end to end of the die.5 The face of the rib at the end where the rolling commences should bemade as narrow as is consistent with its strength, in order that it maybe required to displace but little metal as it enters the blank. Tofacilitate its en- IOO trance, the top may be slightly chamfered orrounded, as indicated by f. I have found that the ribs when the groovesare made to an extreme depth at the entering end, as hereinbeforestated, sometimes break while in action upon the blank, because then theleverage produced by the lateral pressure of the metal upon the ribs isexcessive. Another objection to an extreme depth of the grooves is thatin the process of hardening and tempering the die the root of the narrowribs are much more liable to fracture at such point. In View of suchdefects, and in order to overcome them, I have very materially reducedthe height of the ribs at the entering end, as shown.

In lieu of making the faces of the ribs to at a constant inclinationthroughout the length of the die, they may be curved, the curvaturesomewhat approximating that of a portion of a hyperbolic curve; or thedie itself may be made in sections longitudinally, the inclination ofthe series of ribs of one section varying slightly from its adjacentsection, substantially as set forth and claimed in my United StatesPatent No. 430,237, issued June 17, 1890.

The grooves Z) and the corresponding ribs 11 may be cut by a revolvingmilling-tool, the sides of which give the required inclination to thesides of the ribs, the die-blank being first blocked up at the properangle, if desired, so that the cutters will cut the grooves at thevarying depth, or as shown in Fig. 2. After the cutting-tool has cut oneside of a groove the tool is set over and again operated so as to formthe opposite side of the groove, the blank at the same time being forcedalong past the cutter. After the two sides of the several grooves arecut the standing stock intermediate of the adjacent sides of each groovemay be cut away or routed by a suitable cutting-tool, thus completingthe operation.

A manner of forming the threads of ascrew in a suitable machine, so asto travel back and forth past each other, two similar dies Abeing usedwith the ends reversed. A screw-blank is then placed and held verticallyin the space between the opposed ends of the dies, and as the dies movesimultaneously to the right and left they engage the blank between themand roll it axially until the opposite ends of the dies pass each other,when the jaws of the stationary holder open and the screw drops fromthem. At the commencement of the operation the narrow ends of the ribs aof the dies are forced into the metal to the maximum depth required, or,say, nearly to the dotted line m, Fig. 2, at the corresponding end ofthe dies, and as the rolling pro gresses the metal between the ribs ismore and more compressed and gradually expands into the grooves 12 ofthe dies until, at the end of the operation its fills them and thethread is completed.

I claim- A die for raising the threads of a screw radially from ascrew-blank by rolling, having at the entering end narrow or thin ribsto enter the metal to the required depth, but increasing in width to theopposite end, with the intervening grooves of the same depth or slightlygreater at the entering end than the depth of the groove in the blank,but increasing in depth to the opposite end to correspond with theincreasing height to which the metal is raised as the rollingprogresses.

In testimony whereof I have affixed my signature in presence of twowitnesses.

CHARLES D. ROGERS.

WVitnesses:

CHARLES HANNIGAN, GEO. H. REMINGTON.

